Spark-plug



M. HOFFMANN.

.SPARKQILUGi APPUcATloN FYILED MAY le. 1919.

1,344.892. Patented Jim@ 29,1920.

Sme/who@ f UNITED STATES PATENT ortica MICHEL HOFFMANN, 0F IVNHOE, MINNESGTA, ASSIGNOR OF ONE-HALF T0 F. R.

KLUCZNY, 0F IVANHOE, MINNESOTA.

SPARK-PLUG.

To all 'whom t may concern:

Be it known that I, MICHAEL HOFFMANN, a citizen of the United States, residing at Ivanhoe, in the county of Lincoln and State of Minnesota, have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification. 1

The invention relates to spark plugs for use in connection with the ignition system of an internal combustion engine, the purl pose being to provide a spark plug which is free from the usual insulating core of porcelain or similar material which is susceptible to breakage by heator rough usage. Moreover,l the invention aims to provide a spark plug which is not liable to be easily fouled by carbon, oil or other matter and which therefore does not require frequent cleanlng.A A y The drawing illustrates a referred embodiment-of the invention.-AV owever, it is to -be understood that inladapting the same to meet different conditions, various changes in the form, proportion, andminor details of constructlon may be resorted to without departing from the nature of the invention as claimed hereinafter.

Referring to the accompanying drawing,

Figure l is a view in elevation of a spar: plug embodying thev invention.

Fig. 2 is a vertical central section of the plugshowing the parts on a larger scale.

Fig. 3 is a top View of the plug. l

Fig. 4 is a viewof the lug inverted and as seen from the lower end.)

Corresponding and like parts are referred to in the following description and `1ndi v cated in the several views of the drawing by like reference characters.

The body of the plug consists of a shell l, the upper portion of which is of polygonal form for reception of a wrench or other tool and the 'lower'portion of which is externally threaded for engagement` with the cylinder or head of an internal combustion engine. The upper portion of the shell l is enlarged and internally screwthreaded to receive a gland or nut 2. The center electrode 3 passes through the shell 1 and its upper end is threaded to receive the usual binding nut 4 and its lower end is formed with a shoulder 5, whereby to Specification o Letters Patent. Patented June 29, 1920, i' Application sled may 16,

1919. serial 116.297,569, Y v

limit the upward movement of the electrode and enable the same 'to be cranked to the shell. i v 65 Insulation is provided atl the ends/and l intermediate the plug. The upper insular. tion 6 preferably consists of fiber, such as compressed paper, although any suitable insulating material may be employed.- The lower insulation 7 consists omica, which is provided in a number of layers or disks and which is confined between the shoulder 5v and the lower end of the shell 1.` The intermediate insulation consists of a 'plug 8- of asbestos, or like fibrous materia 'compressed into a solid mass. A number of layers of mica 9 are disposed belowfthe plug 8 and are supported upon theinner shoulder formed at the lower end of the u per 1 enlarged portion of the shell. A- paclng ring 10 of metal, such as copper receives thfej plug 8 and sustains the end thrust of 'the i' gland or nut 2 when the latter is screwed into the shell l to compress the interme-l "5 diate insulation consisting of the plu ,8' and mica 9; The several insulating'e ements are centrally apertured to provlde for the`- c passage of the electrode 3 which latter is g retained in place against endwise displacement by the shoulder 5 and the lower bind ing nut 4.' y It will be observed that the lower end of y the shell is completely closed by the mica 7, thereby preventing any oil or` gases from entering the lower ortion of the Asliellgand fouling the same. t is also observed that the mica 7 is susceptible of resisting a high temperature and the plug being free from insulation of a nature such as porcelain is not liable to be rendered unfit for service by havin the insulation fractured by heat 0r handling Moreover, it is not necessary to take the plug apart for purposes of cleaning because there' is' not liability. for carbon 95 or oil to reach the interior of the plug which isfsealed by the end insulating elements 6 'and 7 j; Thel foregoing descriptionI and the drawf ing have reference to what may be con/s'id- 100 ered the preferred, or approved Aform of my invention. It is to -be understood that I may make such changes in construction and arrangement and combination-of parts,

Bof;

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materials? dimensions, el; Cetera, as nmjf prove expedient und fali wil/hin the seppe 0l the appended claims.

Hau/ing thus fully descibed my inmn tina, what claim as nQW and desir@ 30 S@- cuie by Letters Patent isz-- l. A. spawn: ping, comprising a shell, an insulating claimant Wiliin tlm shell, ay gland 'llnesulcffl lio the Shell and confining tlm insulating element therein, insulating; elezinen'bs closing; the onimond of the shell and gland, un eiectiodc passing tlnxnngli tlnfi gland, slieli and the inn :unl ou m' insulfxiting en'ngnlzs, inczmn :q )plied to opposite und jpoi'timis (if lli@ electrode im' Sncuiing Lim end insuiuling elements, und :in claw ti'mle :it the inner end of the shell copei'- Ming willi lthe inner and olx the eleizt'ifml passing lilnfolugli flic shell und gland to ifmm lli@ spark gap Wholly beyond Llle insulating element at lle inner @mi olf th@ sbc-iii.

closing lille lower anni 01' Lim slnllt pliuibiu insulation cloning lfim upper @nil 0l? lim simil7 insulaling material within 'the :simil inciuding; mica anni :L plug nl fibrous maturi-Lil, u gland threaded into ille, slwll for conl'ining lille in irn'mliuln insulation. un elculfioilc pinning; through linz siwenzll insaulnL-ing elclnents :unl Iii-willed :it its luwcl' und 'with n shouldn' und having its iunior und Lln'eznlcni im' u sinn'l ilisnni-u uml binding nu'lsi niountml upon tlm lliizulnil mul (if the elec-- limlu im' rtnini il: :unl liu uppui' unil, lower insulating civinunls in pusitiun.

i ip-sufi; ping, comprising n, simil, mica' 

